The present invention relates to a play data editing device and a method of editing play data. More specifically, the present invention relates to a technology for editing play data such as Musical Instrument Digital Interface (MIDI), so that the play data is automatically adjusted according to a speaker characteristic of a melody playing device and the like.
A mobile communication terminal such as a cellular phone is typically provided with a melody playing function. The melody plying function is generally used for generating a ring tone upon receiving a call or an electrical mail. Some of the mobile communication terminals are known to have a capability of plying music.
Many of the mobile communication terminals are adopted MIDI as a standard of playing melody. Instead of converting sound to data, according to the MIDI standard, play information of an instrument is converted to data. For example, when the instrument is a keyboard, a playing action such as “pressing a keyboard with a finger”, “releasing a finger from a keyboard”, “pressing a pedal with a foot”, “releasing a foot from a pedal”, “changing a tone”, and the like is converted to data. The play data corresponding to the MIDI standard is called MIDI data.
It is possible to create MIDI data with a personal computer, a MIDI device, and the like. For example, a MIDI keyboard is used for inputting information, and a personal computer edits the information to obtain MIDI data.
MIDI data can be played on an audio system as well as a mobile communication terminal. When a mobile communication terminal plays MIDI data edited for an audio system, however, audio quality tends to be deteriorated. This is because many of mobile communication terminals only have a small speaker. Normally, a mobile communication terminal has a small speaker with a diameter of 1.0 cm or less. In general, a small speaker has a characteristic in which a gain of low pitch sound is smaller than that of high pitch sound. Depending on a type of instrument, it may be difficult to play on a small speaker. Accordingly, when a mobile communication terminal plays MIDI data edited for a large speaker, it is necessary to edit the MIDI data. Patent References 1 and 2 have disclosed technologies for editing MIDI data.
Patent Reference 1 has disclosed a technology in which MIDI data is edited according to a difference in an instrument and a characteristic of a sound generator. In the technology, a sound conversion table includes a relationship between a set volume and an actual play volume according to an instrument, and MIDI data is edited based on the sound conversion table. In the technology of Patent Reference 1, it is possible to adjust only a volume balance depending on a difference in a sound generator, thereby making it difficult to adjust a property other than a volume. Accordingly, it is difficult to use the technology for converting MIDI data for a large speaker to MIDI data for a small speaker.
Patent Reference 2 has disclosed a technology in which accompaniment information is added to existing play data. In the technology, a central processing unit (CPU) detects a chord in play data using a chord table, and an automated accompaniment device creates accompaniment information corresponding to the chord. However, it is difficult to solve the problem associated with a small speaker described above by adding accompaniment.
Patent Reference 1; Japanese Patent Publication (Kokai) No. 2002-258841
Patent Reference 2; Japanese Patent Publication (Kokai) No. 06-295179
In view of the problems described above, an object of the present invention is to provide a play data editing device and a method of editing play data, in which it is possible to prevent deterioration of sound quality due to a difference in a speaker characteristic.
Further objects and advantages of the invention will be apparent from the following description of the invention.